What is skeletal dysplasia?

Skeletal dysplasia is the medical term for what many people refer to as dwarfism. It’s an umbrella term that includes hundreds of conditions that can affect your child’s bone and cartilage growth. Types of skeletal dysplasia are generally classified by which parts of the skeleton are involved.

If your child is born with skeletal dysplasia, they will have abnormal differences in the size and shape of their legs, arms, trunk, or skull. They may be very short in stature. They may also have arms and legs that aren’t in normal proportion with the rest of their body.

Skeletal dysplasia is a genetic condition. It’s caused by a defect in a specific gene, known as a genetic mutation. Each type of skeletal dysplasia is relatively rare. But as a whole, skeletal dysplasia affects close to one in every 5,000 births, report researchers in Genetics in Medicine.

Specific symptoms of skeletal dysplasia vary depending on the disorder that your child has. Their arms, legs, trunk, or skull will likely develop with an unusual shape, size, or both. Other symptoms can include:

  • stubby fingers
  • duplication of fingers or toes
  • club feet
  • missing limbs
  • missing ribs
  • fractured bones
  • joint pain
  • scoliosis
  • developmental delays
  • cognitive impairments (previously known as mental retardation)

Skeletal dysplasia is an inherited condition. It can be caused by many different types of genetic mutations, which are passed down from parents to children. These mutations can prevent your child’s bones from growing normally. While skeletal dysplasia runs in families, you can potentially pass the condition to your child even if you don’t have a known family history of it.

The exact genetic defect responsible for your child’s skeletal dysplasia may be difficult to pinpoint. The most common type of skeletal dysplasia is called achondroplasia. It’s caused by mutations of your child’s FGFR3 gene. Most of the time, parents of children born with achondroplasia have normal height and stature.

Other common types of skeletal dysplasia include:

  • thanatophoric dysplasia, a condition that causes your child to develop extremely short limbs, extra folds of skin on their arms and legs, and underdeveloped lungs
  • hypochondroplasia, a condition that affects the conversion of cartilage into bone in your child’s body and results in short arms and legs, as well as hands and feet that are short and broad
  • campomelic dysplasia, an often fatal condition in newborns that causes dangerous bowing of the long bones in your child’s legs and often their arms as well
  • osteogenesis imperfecta, a disorder that results in fragile bones that break easily
  • achondrogenesis, a disorder that causes your child to develop short limbs and a small body

If your child has skeletal dysplasia, they may be born with a short stature. In other cases, they may be born with a normal stature and fail to grow later on. You or your child’s doctor might discover their condition if your child’s head grows out of proportion to the rest of their body.

To diagnose skeletal dysplasia, your child’s doctor may first conduct a physical examination. They will likely measure your child’s height, weight, and head circumference. They will probably measure the lower and upper segments of your child’s body separately to assess their proportions. They may also ask you questions about your child and family’s medical history.

Your doctor may use X-rays, magnetic resonance imaging (MRI) scans, or computed tomography (CT) scans to help identify and assess deformities in your child’s bones. In some cases, they may even diagnose skeletal dysplasia before your child is born, using an ultrasound examination. Your doctor will likely conduct a routine ultrasound during your pregnancy or your partner’s pregnancy. During the exam, they may notice abnormalities in your developing child’s bone structure or limb lengths. They may order a more detailed follow-up ultrasound to help diagnose their condition. The exact type of dysplasia may be difficult to diagnose until after your child is born.

Your child’s doctor may also recommend genetic and molecular analysis to help identify the type of skeletal dysplasia that your child has. This can help them identify the exact genetic mutation that’s causing their condition.

Your child’s doctor may work with a team of specialists to develop and deliver a treatment plan. For example, these specialists may include neurosurgeons, neurologists, orthopedists, ophthalmologists, endocrinologists, radiologists, geneticists, physical therapists, occupational therapists, and others.

Your child’s doctor may prescribe growth hormones to help boost their growth. This type of treatment involves injections with needles every day. It may help increase your child’s height, but they will probably still develop below-average stature, even with treatment.

Their doctor may also recommend surgery. For example, if your child’s bones are constricting their spinal cord or brain stem, a pediatric neurosurgeon may need to remove some bones. Surgery may also be used to help lengthen your child’s limbs and induce bone growth. But there are many possible complications involved in this type of surgery. It may involve multiple procedures and a long recovery period.

Your child’s doctor may also recommend other treatments and rehabilitative therapies to help relieve their symptoms, increase their independence, and improve their quality of life.

The long-term outlook for your child will depend on the type of dysplasia they have. According to the Children’s Hospital of Philadelphia, about half of fetuses with skeletal dysplasia are stillborn or die shortly after birth. Some children with the condition survive into childhood. Others survive into adulthood. Many of them live relatively normal lives.

Ask your doctor for more information about your child’s specific condition, treatment options, and long-term outlook.